Hemstitching machine



Sept. 21, 1937.

c. HIRSCHI HEMSTI'I'CHING MACHINE Filed Jan. 29, 1956 5 Sheets-Sheet 1IN VE/V T0 W ow Sept. 21, 1937'.

c. HIRSCH HEMSTITCHING MACHINE 3 Sheets-Sheet 2 File d Jan 29, 1936Sept. 21, 1937. c. HIRSCH 2,093,558

' HEMSTITCHING MACHINE Filed Jan. 29, 1936 5 Sheets-Sheet 3 INVEIVTO lor Patented Sept. 21, 1937 UNITED smres masts" HEMSTITCHING MACHINE;

Claude "Hirsch, Paris, France. assignor to Anciens Etablissements R.Cornely & Cie.,

Socit Anonyme, Paris, France, a French company Application January 29,1936, Serial, No".' 61,411 r In France February 7,;1935

2 Claims; ((11. 112-81) The present invention has for its'object theprovisionof a plain or ladder hem-stichin-g machine adapted to operateat verylhigh speeds whilst allowing perfectwork to be obtained at i 5those speeds whatever be the nature of the fabric,

andeven posed. V I H r This result can beobtained, accordingito thepresentinvention in the case of fabrics of small thickness, by theSuppression of the punch arranged between the needles inkno-wnvhem-stitching machines; this obviates the presence of any driving meansfor the punch, such driving means having theeffec't, by reason of itsinertia, of slowingdownthe running of the machine; the auxiliarypiercer; disposed in. advance of the punch in presentmachines, ishowever retained.

When his desired to obtain hem-stitch work having very accuratecontours, even with thick or strong fabrics, it is possible according tothe present invention to arrange behind the needles, in the direction ofadvance of the fabric, a supplementary piercer having for its object theshaping of the aperture after its passage below the needles, the saidpiercer beingof a suitable crosswith a large number of fabricssupersection for that purpose. The machine is then provided withreversing feed, that is tosay that the fabric performs alternatemovements in one direction and in the other, with a greater amplitude inthe direction in which it is first to ad- Vance; That allows in factseveral successive shapings of the apertureby the rear piercer, as

will be explained hereafter.

Moreover, as will be understood, it is possible to add. a rear piercerto existing machines, comprising a punch between the needles, when it isdesired to execute more perfect work with these needles.

The subsequent description, with reference to the annexed drawings given'by way of example, will explain in what manner the invention can becarried out.

Figs. 1, 2, 3 and 1 show in plan the successive stages in the formationof a ladder hem-stitch in ordinaryhem-stitching machines with straight,

feed.

Fig. 4 represents in. plan, diagrammatically, the arrangement of thefore-piercer, punch and needles in these known machines.

Figs. 1d, 2a, 3a and I'd show the stages in the form of a ladderhem-stitch in. known machines with reversing feed.

Figs. 1b, 2b, 3b and lb' represent likewise the stages in the formationof the ladder hem-stitch in a machine according to the invention.

aperture.

Fig. 5 represents in side view the arrangement in this machine of thefore-pircen'needles and rear-piercer serving for the shaping of theFigLG is an end view o f a machine according 5 to. the invention, seenfrom the driving side.

Fig. '7 shows'this machine inlateral elevation, partly in section.

Fig, 8 is an end view of the machine, theside of the needles. 7

Figs. 9 and 10 are partialviews of Fig.1, on alarger scale, showing theneedles and punches, in the positions which they occupy at the stages ofFigs. 1b and 2b (in Fig.9) and 3b (in Fig. lb), Fig. 11 is a partialView of Fig. 5, on a larger scale, likewise showing theneedles,fore-piercer and rear-piercer. e v

Machinesfor plain or ladder hemstitching, hitherto known operate with apiercerorpunch I (Fig. 4) placed betweenthe two needles 2 and. 3; thispunch serves to perforate the fabric and at the same time it accompaniesthe needles in the course of their passage into the fabric, in orderthat they may not leave between them any longitudinal thread ofthejfabric.

f Moreover, another piercer or forepiercer, situated in advance of theneedles (looking at the machine in the direction ofthefsed of thefabric, indicated by the arrow 5) is frequently utilized seen from r inorder to separate the threads of the fabricand. 30

to produce a first perforation forming a blank or rough outline of theaperture.

It is to be noted 'thatwhile the fore-piercer 4 can be mounted and fixedupon the needle-bar, in such a way asto follow the upward anddownwardm'ovement of the needles, it is not the same for the punch I,although this punch works in the same hole of 'the fabric as theneedles. The punch cannot in fact be fixed upon the needle carrier forthat would result in an excessive length for the punch and aconsiderable inertia tobe overcome. This makes it necessary to providefor the punch l a special drive, independent of that for the needles,which makes the movements of the machine sluggish and diminishesconsiderably the possibilitiesof speed. 7

Ladder hem-stitching machines hitherto known, working with the system ofI punch and fore-piercer described above, can operate either withstraight feed or with reversingfeed.

' In the case of the straightfeed', the apertures blanked by thefore-piercer 4 (which passes successively, three times through them.)are there-- after traversed by the punch and needlesas a unit.- As areminder, there will be explained,

with reference to Figs. 1, 2, 3 and l', the various stages in theformation of the stitch with straight feed.

In Fig. l, the fabric has just been fed forward in the direction of thearrow 5 in such a way that the needle threads extending above and. belowthe fabric (below the fabric they are taken on v by the hooks) pull uponthe corners 6 and l of the previously formed aperture B; the needles nowdescend into the aperture C prepared in the preceding stage by thefore-piercer D, and proceed to the taking of the loop with the hooks,then they rise again.

In Fig. 2, the needles descend again, while moving apart and penetrateinto the fabric at the points 8 and 9 either side of the aperture C;then the hole B under the rear-piercer ID, the hole C they move togetherand rise again.

In Fig. 3 they descend once more into the hole 0, proceed to the takingon of the loop with the hooks and rise again.

In Fig. 1', the feeding of the fabric is produced, thus returning tostage I.

All this is well known in the art.

The punch and needle unit which traverses the hole prepared by thefore-piercer, during the descent of the needles, cannot have a square oreven a rectangular cross-section and it is therefore not suitable forobtaining a perfectly square or rectangular shape for the aperture. Itis only ;by the action of the thread tensions that the corners of theaperture can be given a sharp angular shape, and the execution of squarehemstitch apertures is due really to this cause alone. But since thepull of the threads acts generally with great irregularity, thehemstitch is far from presenting the square (or rectangular) hole whichcharacterizes fine work.

A considerable improvement canbe obtained by retaining the same punchand needle system,

but having recourse to reversing feed (Figs. 1a,

2a, 3a, la), because with the threads crossing one another at each rungof the ladder, their tensions act upon the angles of the aperture andgive them a more nearly square shape than with straight feed;hemstitching with reversing feed will be referred to hereafter at thesame time that the operation of the machine according to the presentinvention is described.

This machine comprises, behind the needles 2, 3 (assuming that themachine is looked at in the direction of the general advance of thefabric, that is to say from the position occupied by the operator), apiercer l (see Fig. which can present in cross-section the exact shapewhich it is desired to give the aperture, namely a square shape in thecase illustrated in the drawings; this rear-piercer therefore permitsthe shaping of the aperture and giving it a perfect conformation. Thefore-piercer 4 is retained, but the punch I situated between the needlesin the known machine is suppressed.

This machine operates preferably with reversing feed; in fact, in thiscase, the rear-piercer becomes fully effective for it acts several timesover upon the shape of the incompletely sewn hem-stitch, as will be nowexplained with reference to Figs. 1b, 2b, 3b and l'b.

In Fig. 1b, the needles descend with their points together (see alsoFig. 9) into the hole C prepared in the course of the preceding stage bythe fore-piercer 4, which in the present stage prepares the followinghole D. Within the hole C, where they have thus penetrated withoutleaving any. fabric thread between them, the needles separate whiledescending, until at the taking-on of the loop with the hooks they havea position further apart (see Fig. 10). Then the taking of the looptakes place, as well as the formation of the stitch c c which is drawntight while the needles rise again and. while the backward feed (arrowH) brings the hole C under the forepiercer 4 and the hole B under theneedles, ready for the next stage.

In the second stage (Fig. 2b) the needles descend with their pointstogether into the hole B, already partly sewn (by the stitch b b made ina preceding stage) and shaped by the rearpiercer It). In descending,they move apart for the taking on of the loop and rise again, formingthe stitches b b whilst the forward feed (arrow I 2) takes place for thethird stage, and brings under the needles, and the hole D for the secondtime under the fore-piercer 4.

In the course of the third stage (Fig. 3b) the separated needlespenetrate into the fabric almost vertically and produce the stitches 'yl "y 2. Then a new feed movement in the forward direction takes placefor the next stage, bringing the hole C under the rear-piercer ID (for afirst shaping), the hole D under the needles (like the hole C in Fig.lb) and the portion E of the fabric for a first perforation below thefore-piercer 4. This reproduces the same stage as Fig. 1b; the needlesdescend with their points together into the hole D, and the cycle ofoperations already explained is repeated.

It is to be noted that each apertured portion of the fabric passes, inthis cycle of operations, twice beneath the fore-piercer, twice beneaththe needles in their closed-together position, and twice beneath therear-piercer, which makes in all six graduated operations ofperforation, hemstitching and shaping.

Figs. 6 to 11 represent the general arrangement of a machine allowingthe carrying out of the work described, it being understood that onlythe parts necessary to the understanding of the invention arerepresented in these figures.

Fig. '7 shows in particular the driving means for the vibration of theneedles from the cam transmitting to the needles 2, 3, symmetricalseparating and closing movements, by the intermediary of the connectingrod 2|, regulating segment-lever 22, rod 23, jointed parallelogram 24,rods 25, 26, and needle-carriers 21, 28. The cam 20, which revolves inthe known manner at one. third of the speed of the main shaft of themachine, has a profile suitable for giving the needles 2, 3 the desiredseparations, as a function of the height of the bar 29 which carries thesaid needles.

The feeding of the fabric is effected by the feeder 3 l, driven by asystem well known in itself. This system is composed essentially of thecam 32 for moving the feeder backwards and-forwards,

and the feeder-lift cam 33, the one controlling the movement back andforth of the feedersupport 39 by the intermediary of the levers andconnecting rods 34, 35, 36, 31 and 38, and the other the lifting of thefeeder by the intermediary of the levers and connecting rods 40, 4|, 42and 43, (see Fig. 8).

A special feature of the machine consists in mechanism for controllingthe phase of the lifting of the feeder in relation to the othermovements of the machine.

This'regulation allows of adjusting considerably in relation to oneanother the forward and rearward movements of the fabric, in order to2,093,558 obtain, whatever be the nature of the fabric worked upon,exact amplitudes for the various forward and rearward movements of thefabric, in such a way that the prepared or shaped holes are placed ateach movement in the desired position with relation to the needles andthe piercers.

This mechanism comprises an eccentric bush 44 pivotally mounted on themetal frame of the machine and serving as supporting sleeve for thefulcrum-pin 45 of the arm 40, which controls the rise and fall of thefeeder. Rotation of this bush shiftsjthe pivot 45; consequently theother end of the lever 49, carrying the roller 46 guided in the cam 33,moves along this cam, which brings about the desiredalteration of phase.

In order to facilitate this regulation, the bush 44 is fast with a lever41 of which the other end travels over a sector 48 which may bearsetting marks and upon which it can be locked.

The piercers 4 and [0 are advantageously mounted upon slidable supports49 and 50 (Fig. 11) integral with the needle-carrier bar 29, in such away that it is possible to set each of them at a distance from the planeof the needles corresponding to the length of the stitch.

As regards their cross-section, that of the forepiercer 4 is preferablyoval or circular, whereas that of the rear-piercer l0 presents the finalshape of the hem-stitch aperture (square or rectangular). g

The curved profiles of these piercers are progressive, especially uponthe fore-piercer, in order to separate the fabric threads in a propermanner cating movement, a fore piercer adapted to perforate the fabricprior to its passage under the needles, the space between the needlesbeing wholly free from any punch as is usually provided between theneedles in machines of this type, a rear piercer arranged behind theneedles in the direction of the advance of the fabric, said rear piercerhaving a cross section adapted to exactly shape the hem-stitch apertureafter its passage under the needles, means for actuating said forepiercer and said rear piercer in accordance with the movement of theneedles, a feed mechanism for the fabric including a feeder and meansfor lifting said feeder with respect to the fabric, and regulating meansfor modifying the feed of the fabric, including means for controllingthe phase of the lifting of said feeder with relation to the othermovements of the machine.

2. A hem-stitching machine for obtaining in a fabric hem-stitched workof very clear conformation at very high speed, which comprises, incombination, two needles, means for giving said needles a reciprocatingmovement at right angles to the fabric, means for oscillating saidneedles in a direction transverse to that of said reciprocatingmovement, a fore piercer adapted to perforate the fabric prior to itspassage under. the needles, the space between the needles being whollyfree from any punch as is usually provided between the needles inmachines of this type, a rear piercer arranged behind the needles in thedirection of the advance of the fabric, said rear piercer having a crosssection adapted to exactly shape the hem-stitch aperture after itspassage under the needles, means for actuating said fore piercer andsaid rear piercer in accordance with the: movement of the needles, afeed mechanism for the fabric including a shaft for operating themachine, a cam controlled by said shaft, a feeder for moving the fabric,at least one lever for transmitting to said feeder a verticalreciprocating motion operatively controlled by said cam, a fulcrum forsaid lever, and an eccentric bush adapted to act as a support for saidfulcrum.

CLAUDE HIRSCH.

